Embodiments described herein generally relate to photon detectors.
Avalanche photodiodes (APDs) are generally used for single photon detection. APDs and particularly InGaAs APDs have been the cornerstone for single photon detection in practical quantum communication systems for over a decade thanks to their low cost compactness and cryogen-free operation. Their single photon sensitivity arises from avalanche multiplication with gigantic gain when biased over their breakdown voltage. Biasing below their breakdown voltage causes a loss of single photon sensitivity but even at these biases, the APD remains optically responsive and produces a photo current with a bias dependent gain.
Recently, a weakness has been reported in APD systems that they can be put into a “blinded state” where they are incapable of detecting single photons but where they may be manipulated using higher intensity pulses of radiation.